On MIPS calls to _mcount in modules generate 2 instructions to loadthe _mcount address (and therefore 2 relocations). The mcount_loctable should only reference the first of these, so the second isfiltered out by checking the relocation offset and ignoring ones thatimmediately follow the previous one seen.

However if a module has an _mcount call at offset 0, the secondrelocation would not be filtered out due to old_r_offset == 0being taken to mean that the current relocation is the first oneseen, and both would end up in the mcount_loc table.

This results in ftrace_make_nop() patching both (adjacent)instructions to branches over the _mcount call sequence like so: